Vasoactive intestinal peptide treatment that increases thyroid blood flow fails to alter plasma T3 or T4 levels in the rat.

Vasoactive-intestinal-peptide (VIP)-containing nerve fibers impinge upon both follicle cells and blood vessels in the thyroid gland. We have previously shown that VIP induces a specific, dose-related increase in thyroid blood flow in the rat. However, our VIP treatments had no effect on circulating thyroid hormone levels.

VIP and its homologues increase vascular conductance in certain endocrine and exocrine glands.

The effects of vasoactive intestinal peptide (VIP) and related structural homologues on tissue vascular conductances were investigated in anesthetized male rats. VIP, peptide histidine isoleucine (PHI), secretin, growth hormone-releasing factor (GHRF), gastric inhibitory peptide (GIP), or saline was infused intravenously over 4 min. Tissue blood flows were measured during this time by use of 141Ce-labeled microspheres.

Effects of thyrotropin on the vascular conductance of the thyroid gland.

It is well established that TSH from the anterior pituitary is the principal stimulatory agent in the physiological regulation of the thyroid gland. Chronic elevations of plasma TSH induce hyperplasia and hypertrophy of thyroid follicular cells and enlargement of blood capillaries. At low plasma TSH levels the thyroid gland atrophies.

Early development of the thyroid axis in the Brattleboro rat.

Plasma concentrations of thyrotrophin (TSH), thyroxine (T4), and triiodothyronine (T3), and pituitary TSH concentrations were determined at weekly intervals during the first 42 days following birth in Brattleboro homozygous (DI), Brattleboro heterozygous (HZ), and Long-Evans (LE) rats. Offspring from matings of Brattleboro rats were divided into DI and HZ animal subgroups on the basis of hypothalamic vasopressin content. In control LE rats, circulating levels of TSH, T4, and T3, and pituitary TSH concentrations increased during the early postnatal period to reach relatively stable levels between 28 and 42 days of age.

Changes in episodic luteinizing hormone secretion leading to puberty in the lamb.

In this study, we monitored episodic luteinizing hormone (LH) secretion throughout development in eight April-born ewe lambs to determine if a change in LH pulse patterns preceded first ovulation at puberty. LH pulses were measured in samples collected every 12 min for 6 h once in July, twice a month from 22 August to 2 October, and then weekly until puberty. Progesterone concentrations, measured in samples taken 3/wk, were used as an index of first ovulation, which occurred at 29.

Neuropeptide control of thyroid blood flow and hormone secretion in the rat.

The effects of peptide HI (PHI), neuropeptide Y (NPY), and substance P (SP) on thyroid blood flow and hormone levels were studied in anesthetized rats. Regional blood flows were determined using radioactive microspheres. No change in heart rate or mean left ventricular pressure occurred during these neuropeptide infusions (0.

Effects of vasoactive intestinal peptide on thyroid blood flow and circulating thyroid hormone levels in the rat.

The effects of vasoactive intestinal peptide (VIP) on thyroid blood flow and hormone levels were studied in rats. Tissue blood flow was determined from the distribution of radioactive microspheres after injection by cardiac puncture directly into the left ventricle of anesthetized rats. Initial results indicated that the systemic infusion of 6.

Immunocytochemical studies of the peptidergic innervation of the thyroid gland in the Brattleboro rat.

An indirect immunofluorescence technique was used to study the peptidergic innervation of the thyroid gland in homozygous Brattleboro rats (DI) and normal Long-Evans rats (LE). The primary goal of this study was to determine whether the previously demonstrated decrease in thyroid responsiveness to TSH in DI might be due to an abnormality in the innervation of the thyroid. Thyroids from both types of rats were found to contain nerve fibers containing immunoreactivity for vasoactive intestinal peptide (VIP), substance P (SP), neuropeptide Y (NPY), and peptide HI (PHI).

Influence of left ventricular receptor stimulation on plasma vasopressin in conscious dogs.

The current study was undertaken to determine whether receptors in the left ventricle are capable, when stimulated, of inhibiting plasma arginine vasopressin (AVP) in the conscious dog. Dogs were instrumented to measure aortic pressure and heart rate. In addition, a catheter was implanted in the left circumflex coronary artery.

Renal function and pituitary hormone release during cerebral osmostimulation and TRH in dogs.

The effects of increases in serum osmolality on renal function and plasma levels of radioimmunoassayable prolactin (PRL) and luteinizing hormone (LH) were examined during intracarotid (IC) infusions of hypertonic NaCl in conscious dogs with a sustained water diuresis (SWD). A 10 minute bilateral IC infusion of 45 mumole/kg X min X artery of NaCl during SWD which raised jugular osmolality by 10.1 mOsm/kg, without significantly altering peripheral venous osmolality, produced a significant decrease in free water clearance (CH2O) at 20 to 40 minutes postinfusion.

Carotid sinus baroreceptor activity in the nonhuman primate.

The carotid sinus of eight adult Macaca fascicularis monkeys was functionally isolated from the circulation and perfused with Krebs-Henseleit solution. The impulse activity in 65 carotid sinus baroreceptor fibers from the left carotid sinus nerve was studied during nonpulsatile perfusion and was compared with the impulse activity in 68 fibers from 10 adult mongrel dogs. Curves relating the discharge frequency to carotid sinus pressure were constructed.

Arginine vasotocin and renal function in the conscious dog.

The effects of arginine vasotocin (AVT), 4-6 ng/kg, on renal function and plasma prolactin (PRL) were determined in conscious American foxhounds undergoing a water diuresis. Intravenous AVT produced an antidiuresis, kaliuresis and inconsistent natriuresis, independently of changes in GFR, blood pressure, heart rate and plasma PRL.

Communicating hydrocephalus caused by Aspergillus flavus.

A patient with a past history of sporadic parenteral drug abuse had communicating hydrocephalus associated with arachnoiditis over the lumbar spinal cord. The diagnosis of aspergillosis was made by a newly described immunofluorescent staining procedure and was later confirmed by culture. The spectrum of central nervous system aspergillosis associated with drug abuse is reviewed.

Intravenous metronidazole therapy for Bacteroides fragilis meningitis.

A 69-year-old man developed meningitis due to Bacteroides fragilis and Streptococcus MG-intermedius, which progressed during chloramphenicol and nafcillin therapy to the extent that he seemed near death, with frank pus covering the spinal cord at surgery. Treatment with intravenous metronidazole and penicillin G was curative. After multiple trauma, a 20-year-old man developed meningitis due to Escherichia coli and B fragilis.